Device and method for treating refrigerators



Feb. 19, 1935. s, SAFFQRD 1,991,702

DEVICEA AND METHOD FOR TREATING REFRIGERATORS Filed Aug. '7, 1931 2 Sheets-Sheet l DEVICE AND METHOD FOR TREATING REFRIGERATORS Filed Aug. 7, 1951 2 sheets-sheet 2 Patented Feb. 19, 1935 'UNITED STATES DEVICE AND METHOD Fon TREATING REFBIGERATORS Truman Sunderland Safford, Harrison, N. Y. Application August 7, 1931, Serial No. 555,739

'12 claims.

o frigerating surfaces, and to a novel refrigerator adapted to operate always at full efficiency without frosting of its refrigerating surfaces.

" cording to my invention.

Prior to my invention, great trouble'has been experienced with the deposition and freezing of moisture upon the refrigerating surfaces of mechanical refrigeration systems. Such frosting, as it is called, has been recognized as a great handicap to full realization of efllciency in refrigerating systems, because the more or less por#- ous deposit of ice constitutes a very poor conductor of heat; and, as it may build up to the better part of an inch in thickness before being removed, it may very seriously reduce the heat exchanging, capacity of the refrigerating surface upon which it is deposited. This diillculty has heretofore been regardedas inherent in artificial refrigeration systems, since the 'cooling fluid must be maintained below the freezing point of water, and being accepted as inevitable it has been treated, when the ice accumulated to ltoo great an extent, by closing down the part of the plant affected and warming the refrigerating surfaces until the ice has been melted away. This practice involves both inconvenience and expense, and in some cases may even involve substantial loss because of failure of the refrigerator to maintain the required temperatures.

It is an` object of my invention to provide for the continuous operation of refrigeration systems at full eiliciency without frosting of the refrigerating surfaces even when they are maintained well below 0 C. It is also an object of the invention to avoid the necessity for shutting down and defrosting the refrigerating ,parts of the system.

In the acompanying drawings I have `illustrated the-application o f ymy invention to a household refrigerator of the mechanical or electrical type.

Figure 1 illustrates such a'refrigerator with a refrigerating unit embodying my invention. v

Figure .2y shows a front elevation of the refrigerating unitvwith certain parts ybroken' away.

' Figure' 3 shows a vertical longitudinal section taken on line 3-3 of Figure, 2.

, Figure 4 shows averticalcross section vtaken on line d-of Figure Fig. 5 is a diagrammatic View of arefrigerator embodying a `recirculating antifreezevdevice ac- The refrigerating unit as shown in the' draw-v ings is a common type of expansion or evaporation chamber for the refrigerant fluid. As shown this chamber has an outer heat exchange wall 10, and a cabinet formed centrally therein for reception of the trays 11 for the freezing of ice cubes, desserts etc.

Over the top of this refrigerating unit is fitted a cap 13 of a water soluble material adapted to dissolve in the water of condensation sufficiently to prevent freezing of such condensed moisture. This cap may cover any desired part of the cool-- ing surface or the entire surface, but I have found it most desirable to provide such a cap only over the uppermost portion of the unit and to utilize a material which will be sufllciently soluble to form an anti-freeze liquor, which in flowing down over the remaining surface will mix with any additional moisture which may condense thereon and will prevent the freezing of such mixture.

It is desirable, altho not essential, that some means be provided to prevent the trickling of the condensed water from the cap 13 down the side of the cooling unit in more or less widely separated streams. For best results the condensed moisture with its dissolved anti-freeze should flow as uniformly as possible` over the cooling surfaces. If the surface of the cooling unit is of a material which is uniformly wetted by water or is treated to render it so, or if the anti-freeze material is adapted to lower the surface tension of the water of condensation suciently to cause it to wet the cooling surfaces uniformly no other precaution is necessary -to assure the uniform prevention of frosting. If on the other hand it is desired' to use a surface andan anti-freeze material such that the surface will not be evenly wetted, any of a number of expedients may be adopted to prevent haphazard vtrickling.A For example, as illustrated inFigure l, the surface of the cooling unit may be formed into fine-grooves or corrugations, or, as shown in Figures 3', 4 and 5 av jacket may be fitted over the cooling unit to conduct the condensed moisture over its sides. 'I now prefer to make. this jacket of cotton net; altho'it may be made of many othermaterials, e. g. wire Anetting as well as othertextile'materials. ,c l If it is the ice trays l1 into the cabinet,l means may be providedvjfor leading the `antifreeze solution along theirv sides'andfbottom. In the dra..jings I have shown a trough 15 which catches the condensationdraining fromabove the trays, at once preventing 'itfrom reaching the inside of the desired also to Aprevent the freezing of trays and diverting it for defrosting the sides of most tray. A second trough 17 at the front of the partition 18, upon which the tray rests, collects the anti-freeze, after it has iiowed over the sides of the tray 11 and the partition 18, and

conducts to the tubes 19, through which it drains to the side of the next tray. From the bottom tray a trough 20 similar to the trough 17 leads the solution to a tube 21, through which it passes directly to a drain pipe, or to the collecting basin 22. This basin 22, as shown. is made to collect 'also the drip from the sides of the cooling unit.

It may be merely a pan, which must be emptied periodically or it may be connected to a drain '7.

It will be understood of course that if the defrosting is to be entirely effective, the condensation water must dissolve from the cap 13 enough of the anti-freeze so that the solution diluted by additional condensation water will be, as it reaches the bottom of the cooling unit, barely freezeable at the temperature thereof. Some freezing may be allowed to occure during the period when the refrigerator is operating if it is not greater than can be melted during the subsequent period while the refrigerator is idle, but preferably enough of the anti-freeze is dissolved to prevent freezing at any time. Beyond such amount, however, any further solution of the anti-freeze is waste, and accordingly should be avoided.

lThe amount of the anti-freeze which goes into solution is governed primarily by the choice of an anti-freeze material of suitable solubility. Given any particular material, however, I may further control the extent of its solution by various other expediente. The physical form of the material in the cap may control, e. g., whether in dense crystalline form or porous or as a loosely aggegated and lightly cemented powder. Again, I may utilize the cooling of the cap by the cooling unit to control the extent of solution, i. e., by putting the cap in direct contact or insulating it from the cooling unit I may control the tem-V perature and thereby both solubility and the extent of condensation at the surface of the cap. It may also be desirable in some cases to use additional bands of the anti-freeze positioned about the sides of the cooling unit to buildup the solution after it has become diluted by additional water of condensation.

The choice of the particular anti-freeze will depend upon the conditions in which it is to be used. Cost, solubility, toxicity, odor, stability, inertness are among the important considerations upon which the choice will depend. It is obviously unnecessary to enumerate the large number of compounds which may be used under one condition or another. Common salt (NaCl) may be mentioned as one material capable -of use under many conditions, calcium chloride as another. Since, however, the brines of sodium and calcium chlorides are corrosive to some materials, it may in some cases be necessary or desirable to choose another soluble material.

Where provision is made for use of a liquid refrigerant, it is possible to effect economies 'of operation by recirculating the anti-freeze material.

if it is a liquid, or .a strong solution, if it is either liquid or solid. The drip from the sides of the cooling unitmay bepassed counter-current over the condensing coils of the refrigerating apparatus, and a current of air passed counter current to the flow of .the liquid. In this way advantage may be taken of the low temperature of the drip and of the heat of evaporation of the water to cool the condensing coils, while the heat generated by the refrigerating apparatus serves to evaporate the excess water from the'anti-freene material and to concentrate the solution to a point such that it may be returned and recirculated over the cooling unit. It will be understood of course that in specifying counter current ilow I intend only to recommend the best procedure,

, and that such ow is not essential.

In Fig. 5 I have illustrated such an apparatus. The cooling unit of the refrigerator I have indicated by the 'reference character 30. From this, the refrigerator vapors are drawn back through a connection 31 to a compressor 32, and the compressed refrigerant passes through the connection 33 to the condenser 34, and thence through a connection 35 and an expension valve or float chamber 36 back to the cooling unit 30. The compressor 32 is driven by an electric motor 37. This represents a conventional compresser type refrigerating system.

Above the cooling unit is a perforated pipe 38 adapted to spray or drip a liquid anti-freeze material, e. g., a brine solution, onto the top of the cooling unit 30. This material, in flowing down over the unit 30, dissolves the water of condensation which is precipitated onto the cooling surfaces thereof so as to form a nonfreezing solution therewith, and the solution thus diluted passes down into the tray 39, and thence through the' outlet 40 onto the refrigerant condenser coil 34, where it serves to cool the compressed refrigerant, and at the same time, by absorbing heat therefrom, is more readily concentrated by evaporation of water to a current of air blown over the coil by the fan 41. A

The concentrated anti-freeze liquid which drops from the bottom of the coil 34 is caught by the pan 42 and returned through the connections 43 and 44 by means of the circulating pump 45.

In Fig. 5we have shown these various elements of the combination in diagrammatic form, since they represent units which are well known to the art in various forms, and since the present invention is not dependent upon the use'of any particular form.

Altho I have shown in the accompanying drawings and have described above one embodiment of` my invention, and various modications thereof, it is to be understood that many other modifications 'and changes may be made within the scope of this invention, and that the invention may be used with numerous other types of cooling devices than that specifically described and shown inthe drawings, and that the invention may be embodied in many other forms.

I claim:

1. A defrosting device for use in a refrigerating apparatus which comprises a cake of water-solu- .ble solid anti-freeze material adapted to be placed condensed moisture on said member will form an anti-freeze solution of vsufficient strength to prevent cumulative freezing thereon, and a covering of textile net over the cooling surface below the means for supplying anti-freeze materials, whereby the anti-freeze solution will be conducted by said net evenly over the cooling surface.

4. A non-frosting cooling unit comprising a cold heat-exchange member, means for supplying water soluble anti-freeze material to condensed moisture on an upper part of the heat-exchange surface of said member at a rate such that the condensed moisture on said member will form an anti-freeze solution of sufficient strength to prevent cumulative freezing thereon, said cold heat-exchange member including-trays surrounded thereby, and a gutter over the entrance for said trays adapted to prevent the dripping of anti-freeze solution thereinto. t

5. A non-frosting cooling unit comprising a cold heat-exchange member, means for supplying water soluble anti-freeze material to condensed moisture on an upper part of the heat-exchange surface of said member at a rate such that the condensed moisture on said member will form lan anti-freeze solution of sufiicient strength to prevent cumulative freezing thereon, said cold heat-exchange member including trays surrounded thereby, a gutter to collect the antifreeze' solution flowing over the cooling surface above said trays, and conduits to lead said solution from the gutter. to the sides of said trays to prevent their freezing to the cooling unit.

6. The method of defrosting heat -absorbing surfaces of a mechanical refrigerating apparatus which comprises causing a water-soluble antifreeze liquid to flow down over said heat absorbing surface, collecting from the bottom of said surface the drip consisting of the anti-freezev diluted with water condensed from the atmosphere, passing said diluted anti-freeze over a heat-dissipating surface of the refrigerator cycle, whereby to c'ool said heat dissipating surface, and to concentrate the diluted anti-freeze by evaporation of water therefrom, and thereafter returning the concentrated anti-freeze liquid to the heat-absorbing surface for reuse in the cycle.

'7. The method of disposing of water of condensation from refrigerating systems which comprises taking up said water into an anti-freeze liquid, passing the thus diluted anti-freezeliquid in extended form into intimate heat-exchange relation with refrigerant in the high'temperature side of its cycle, evaporating water of condensation from the liquid by means of heat absorbed from the refrigerant, and returning the antlfreeze liquid thus concentrated for reuse in the cycle.

8. A non-frosting cooling unit comprising a cold heat-exchange member having its topV sur-l face so broad as alone to hold a layer of solid water-soluble anti-freeze material and a layer of water-soluble solid anti-freeze material exposed on said top surface in heat-exchange relation thereto and in the path of moisture-laden air currrents which pass over said member so that moisture will be condensed thereupon from said air currents, whereby said water-soluble material will be dissolved to form an anti-freeze solution.

9. A non-frosting cooling unit comprising cooling surfaces and a cake of a water-soluble solid. anti-freeze material, being so closely fitted to a cooling surface thereof, and being so dense and of such thinness, that gases passing over the surface of said cake will be substantially cooled and a substantial portion of their contained moisture condensed onto said cake by transfer of heat therethrough to said cooling surface.

10. A non-frosting cooling unit comprising cooling surfaces and a mass of a water soluble solid anti-freeze material, an exposed surface of which is in heat-exchange relation to said cooling surface such that gases passing over the surface of said mass are substantially cooled and a substantial portion of their moisture condensed onto said mass by transfer of heat therethrough to said cooling surface. v,

11. The method of counteracting frosting tendency of a refrigerator which comprises covering a cooling surface thereof with a mass of solid water-soluble anti-freeze material, and cooling said mass to a temperature at which moisture will condense from the atmosphere around said mass onto its surface, whereby some of the antifreeze material will be dissolved in said condensed moisture and will prevent freezing thereof.

l2. The method as defined in claim l1, in which the cooled anti-freeze mass is held in a position above another cooling surface so that condensation from said mass with anti-freeze material dissolved therein flows down over the latter cooling surface and the cooling of the anti-freeze mass is regulated relative to cooling of said other surface so that the anti-freeze carried from the former to the latter by condensed moisture will prevent cummulative freezing thereon.

TRUMAN S. SAFFORD. 

